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<table width="100%" summary="page for flchain"><tr><td>flchain</td><td style="text-align: right;">R Documentation</td></tr></table>

<h2>Assay of serum free light chain for 7874 subjects.</h2>

<h3>Description</h3>

<p>This is a stratified random sample containing 1/2 of the subjects from
a study of the relationship between serum free light chain (FLC)
and mortality.  The original sample contains samples on
approximately 2/3 of the residents of Olmsted County aged 50 or greater.
</p>


<h3>Usage</h3>

<pre>data(flchain)</pre>


<h3>Format</h3>

<p>A data frame with 7874 persons containing the following variables.
</p>

<dl>
<dt><code>age </code></dt><dd><p>age in years</p>
</dd>
<dt><code>sex</code></dt><dd><p>F=female, M=male</p>
</dd>
<dt><code>sample.yr</code></dt><dd><p>the calendar year in which a blood sample
was obtained</p>
</dd>
<dt><code>kappa</code></dt><dd><p>serum free light chain, kappa portion</p>
</dd>
<dt><code>lambda</code></dt><dd><p>serum free light chain, lambda portion</p>
</dd>
<dt><code>flc.grp</code></dt><dd><p>the FLC group for the subject, as used in the
original analysis</p>
</dd>
<dt><code>creatinine</code></dt><dd><p>serum creatinine</p>
</dd>
<dt><code>mgus</code></dt><dd><p>1 if the subject had been diagnosed with
monoclonal gammapothy (MGUS)</p>
</dd>
<dt><code>futime</code></dt><dd><p>days from enrollment until death.  Note that
there are 3 subjects whose sample was obtained on their death date.</p>
</dd>
<dt><code>death</code></dt><dd><p>0=alive at last contact date, 1=dead</p>
</dd>
<dt><code>chapter</code></dt><dd><p>for those who died, a grouping of their
primary cause of death by chapter headings of the International
Code of Diseases ICD-9</p>
</dd>
</dl>



<h3>Details</h3>

<p>In 1995 Dr. Robert Kyle embarked on a study to determine the
prevalence of monoclonal gammopathy of undetermined significance
(MGUS) in Olmsted County, Minnesota, a condition which is
normally only found by chance from a test (serum electrophoresis)
which is ordered for other causes.  Later work suggested that one
component of immunoglobulin production, the serum free light chain,
might be a possible marker for immune disregulation.  In 2010
Dr. Angela Dispenzieri and colleagues assayed FLC levels on those
samples from the original study for which they had patient permission and from
which sufficient material remained for further testing.  They found
that elevated FLC levels were indeed associated with higher death
rates.
</p>
<p>Patients were recruited when they came to the clinic for other
appointments, with a final random sample of those who had not yet
had a visit since the study began.  An interesting side question is
whether there are differences between early, mid, and late recruits.
</p>
<p>This data set contains an age and sex stratified random sample that
includes 7874 of the original 15759 subjects.  The original subject
identifiers and dates have been removed to protect patient identity.
Subsampling was done to further protect this information.
</p>


<h3>Source</h3>

<p>The primary investigator (A Dispenzieri) and statistician (T
Therneau) for the study.</p>


<h3>References</h3>

<p>A Dispenzieri, J Katzmann, R Kyle, D Larson, T Therneau, C Colby,
R Clark, G Mead, S Kumar, 
LJ Melton III and  SV Rajkumar (2012).
Use of monclonal serum immunoglobulin free light chains to predict 
overall survival in the general population,
Mayo Clinic Proceedings 87:512-523.
</p>
<p>R Kyle, T Therneau, SV Rajkumar,
D Larson, M Plevak, J Offord,
A Dispenzieri, J Katzmann, and LJ Melton, III, 2006,
Prevalence of monoclonal gammopathy of undetermined significance,
New England J Medicine 354:1362-1369.
</p>


<h3>Examples</h3>

<pre>
data(flchain)
age.grp &lt;-  cut(flchain$age, c(49,54, 59,64, 69,74,79, 89, 110),
               labels= paste(c(50,55,60,65,70,75,80,90),
                             c(54,59,64,69,74,79,89,109), sep='-'))
table(flchain$sex, age.grp)
</pre>


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